Would it be a bad idea to separate the runt into HT to fatten it up?

[Heckel&jyde]

I have 10 juveniles ranging from approx 2.5" to 3.5", all from same batch. Initially the runt seemed to be catching up in size but in the past week or so I've noticed its not doing as well. Its very slow to get to the food and gets pushed aside. I don't think its getting enough to eat. Sometimes it looks dark in colour and weak. It comes out at feeding time but seems slow to attempt to eat.

Would it be silly to remove it and put it in the hospital tank for a few weeks to feed it up on FDBW without the competition of the others? I don't want to stress it out by being on its own but I'm worried it will continue to fade away if I don't do something.

Bit of background info:

I'm a newbie. I jumped in the deep end 3.5mths ago by buying 10 fry to raise. The breeder said they were about 4wk old. So I'm learning as I go. (and I read a lot of the grow out challenge thread which was a wealth of information)

They're doing quite well considering my inexperience. There were 2 that were smaller at the start but they caught up in size.

I removed the substrate, converted to bare bottom. Set up hose system so I can do big water changes. Currently do 50 - 70% daily or every second day (which is what I can manage with busy work schedule). Feeding combination of FDBW mostly, plus Hikari discus granules, Sera flakes. And a few weeks ago I made up my first beef heart mix and started feeding that as well. I noticed the bigger 3 have a growth spurt and become more aggressive since feeding BH and the smaller one started to go backwards at that point.

I'm thinking of pulling him out of the main tank and putting him in the small 60L tank to feed it up on FDBW (his favourite food) and maybe to treat him with meds if he's not improving.

All of them have been wormed with flubendazole twice since I had them. The tank is kept at 29celcius. I'm in Australia

[FishFanMan]

I don't see any problem with your plan. From my limited experience in raising juvies once they become runts, they never get close to full size. But why not give it a shot.